Conventionally, in competitive type games, various methods have been employed as methods of gauging the skill level or capabilities, that is, the strength, of a player in that competitive game. For example, these include a percentage of wins or a total value of a required parameter or the like. In a mahjong game, there are yellow dragon levels and the like depending on the percentage of wins and the number of orbs held that have been passed on from a loser to a winner, but considering the percentage of wins for example, in addition to a percentage of wins for which first place has been acquired, it is conceivable that giving consideration to a percentage of fourth place would also be necessary, and therefore there is doubt as to whether a truly strong player is determined by the only the percentage of wins. In this manner, neither of these is sufficient as an indicator for gauging strength.
On the other hand, in competitive type games, methods are known of managing the real capabilities of each player using indicators known as ratings. These indicators accurately show what degree of difference there is in real capabilities by comparing numerical values of each player, and have long been employed by international chess associations and the like.
Patent Document 1 describes employing rating values in determining rankings among teams in a team format competitive contest, and Patent Document 2 describes a calculation method of rating values as an indicator that indicates skill levels in a game.
Incidentally, in rating systems, since values are increased and decreased in accordance with rules to winners and losers after a competition, it is conceivable that a mean value of rating values held by all the players would be a predetermined value, but it is evident that the mean value of ratings decreases over a long continued period of use of the rating system. For example, in the mid 1970s, it became clear that the mean rating in the United States Chess Federation (USCF) was becoming lower, and various measures were devised to deal with this including using bonus points. The reason for this is unclear, but it is thought to involve that the ratings of new members are below the mean point and the ratings of resigning members are above the mean. Furthermore, it cannot be said that the opposite phenomenon of a rising mean value of ratings does not occur.
When the mean value of ratings fluctuates in this manner, it becomes difficult to grasp one's own strength among all the players as a result of the mean value fluctuating even when there is no change in one's own rating, and there is a risk that the reliability of ratings as an indicator is impaired. Neither Patent Document 1 or 2 describes a method for addressing this issue.
Patent Document 1: Japanese Patent Application Laid-open No. 2004-298234
Patent Document 2: Japanese Patent Application Laid-open No. 2006-254979